I see, interesting read!
Two people helped me with fixing the Linux support for my plugin on paper: Fixed lint and build errors on Linux by TekuConcept · Pull Request #64 · microdee/UE4-SpaceMouse (.com)
The only platform specific low level code in there are the platform implementations of the HIDAPI library abstraction. Nothing else should be Windows only. I can only test on windows at the moment though.
In the past I wanted to have first class Mac support but I’ve got frustrated with how Apple things work. I have problems specifically with how the space mice handled there as a mouse before 3DConnexion drivers, and then as a locked device owned exclusively by said drivers. HidManager (iirc the name) then denies HID protocol level access to the spacemice from any other software. -SpaceMouse/issues/4#issuecomment-801526344
Python is not great for Unreal Plugin development. Besides you can engineer your C++ code so it can be cross-platform with the least possible approach